package com.smart.util;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import java.nio.charset.StandardCharsets;

public class EncryptUtils {

	private static String strParam = "Passw0rd";

	private static Cipher cipher;

	private static IvParameterSpec iv = new IvParameterSpec(strParam.getBytes(StandardCharsets.UTF_8));

	private static DESKeySpec getDesKeySpec(String source) throws Exception {
		if (source == null || source.length() == 0) {
			return null;
		}
		cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
		String strKey = "Passw0rd";
		return new DESKeySpec(strKey.getBytes(StandardCharsets.UTF_8));
	}

	/** 对称加密 */
	public static String desEncrypt(String source) throws Exception {
		DESKeySpec desKeySpec = getDesKeySpec(source);
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
		SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
		cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
		return byte2hex(cipher.doFinal(source.getBytes(StandardCharsets.UTF_8))).toUpperCase();
	}

	/** 对称解密 */
	public static String desDecrypt(String source) throws Exception {
		byte[] src = hex2byte(source.getBytes());
		DESKeySpec desKeySpec = getDesKeySpec(source);
		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
		SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
		cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);
		byte[] retByte = cipher.doFinal(src);
		return new String(retByte);
	}

	private static String byte2hex(byte[] inStr) {
		String stmp;
		StringBuilder out = new StringBuilder(inStr.length * 2);
		for (byte b : inStr) {
			stmp = Integer.toHexString(b & 0xFF);
			if (stmp.length() == 1) {
				// 如果是0至F的单位字符串，则添加0
				out.append("0").append(stmp);
			} else {
				out.append(stmp);
			}
		}
		return out.toString();
	}

	private static byte[] hex2byte(byte[] b) {
		int size = 2;
		if ((b.length % size) != 0) {
			throw new IllegalArgumentException("长度不是偶数");
		}
		byte[] b2 = new byte[b.length / 2];
		for (int n = 0; n < b.length; n += size) {
			String item = new String(b, n, 2);
			b2[n / 2] = (byte) Integer.parseInt(item, 16);
		}
		return b2;
	}

	public static void main(String[] args) throws Exception {
		System.out.println(desEncrypt("1234456123445677"));
		System.out.println(desDecrypt("0401200372186BC9640D74433AF7975B8FC6DEC59E2D5360"));
	}

}